Base for surveying instruments.



G. L. BERGER.

BASE FOR SURVEYING INSTRUMENTS.

APPLICATION FILED MAR. 31, 1905.

906,680. Patented Dec. 15,1908.

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mamwm m. {W L- i w W w w w CHRISTIAN L. BERGER, OF BOSTON,MASSACHUSETTS.

BASE FOR SURVEYING INSTRUMENTS.

Specification of Letters Patent.

Patented Dec. 15, 1908.

Application filed March 31, 1905. Serial No. 253,032.

To all whom it may concern:

Be it known that I, Crnns'rmiN L. Banana, a. citizen of the UnitedStates, residing at Boston, in the county of Suffolk and State ofMassachusetts, have invented an Improvement in Bases for SurveyingInstruments, of which the following description, in

connection with the accompanying drawings, is a specification, likeletters on the drawings representing like parts.

In certain situations, as for instance in mine surveying, it isfrequently impossible to employ the usual tripod support for thedifferent surveying lllStl'Llll'lBlll'S on account of the low stoping orspecial condition which makes it impossible to set up the instrument inthe usual manner, and accordingly the head of the instrument is commonlyremoved and placed on a beam or other ledge and sometimes on the ground,being held in position sometimes by a screw-ring or base, and at othertimes by a trivet or tribrach, the latter heretofore consisting simplyof three small legs extending inwardly and upwardly to a threadedringlike center for receiving the threaded end of theii'istriunent-head.

My invention resides in providing a trivet having a broader base thanthe instrument itself provides, and carrying adjusting means whereby theinstrument may be freely turned and shifted without disturbing thetrivet, until it is centered with the plumb bob (usually hung overheadin such work).

A further object of my invention is to provide great stability andcertainty of posi tion by means of the trivet.

In the drawings, Figure l is a perspective view of the preferredembodiment of my invention, showing a portion of a surveying instrumentin operative position thereon; Fig. 2 is a top plan view of the trivetrepre senting the adjustments thereof in dotted lines; and. Fig. 3 is avertical, sectional view taken on the line 33, Fig. 2.

It will be understood that by the term trivet. I do not intend to limitmyself to three legs, but use the word, as commonly used, to mean arigid, low'base or support.

As herein shown I provide three branching diverging legs a, a, 66-, eachhaving a short pointed end or foot a depending from the narrow outer endof the leg proper, the latter rapidly thickening as indicated at (0,until it joins a heavy central cylindrical cup-shaped hub 54''containing a central, vertical, cup-shaped cavity. At its upper end theentire trivet is provided with a plane surface u, corresponding ingeneral outline to the legs and hub and overhanging the latter. asclearly indicated in the drawings. Said legs have their lower and uppersides extending respectively from the bottom portion of said hub andfrom the outer portion of the plane top of the trivet and thenceconverging toward the outer ends of 'the legs, and each leg also has itsopposite upright sides converging towards its top and diverging from theouter end of the leg along its bottom portion to the hub, whereby theleg is broader at its bottom side than in its upper portion. and iswider and heavier at the hub than at its outer end. The hub a has anarrow, inwardly extending flange at its under side and a threadedannulus a at its upper side. Resting on the plane top a is a ring 7)having three projecting arms 1) which is perfectly free to shift in anydirection on the flat top a. Cooperating with the threaded annulus a isa threaded nut b for clamping and retaining the instrument and shiftingring 7) stationary having a laterally extending cap or flange I) tittingflat against the smooth top surface of the ring Z), the latter having aninternal opening considerably larger than the nut b, as clearly shown inFig. 3. For convenience the nut 7) is provided with wings 5*, whereby itmay be quickly turned into clamping engagement with the ring D orloosened therefrom as desired so that when loosened, the ring Z) may beshifted axially or in any other direction, as indicated in dotted linesin Fig. 2.

Depending through the nut b which is provided for the purpose with anopening If, is a stem (3 internally threaded at its upper end at c toreceive the usual threaded end (Z of the inst rument D and threaded atits lower end at to receive a star nut c for adjusting the instrument inclamped relation. with the trivet or base-support which constitutes myinvention. The stem c has a 'llange c for preventing its droppingthrough the trivet when released from the instrument and the star nut ccarries a hemispherical. bearing 0 bearing in a plate 1; adapted toengage the under side of the hub a when the instrument is tightened inplace. At its lower end the stem 0 carries a thumb nut for turning theentire stem so as to screw the threads 0 upon the threaded end (Z of theinstrument.

At their outer ends the arms I) are provided with sockets b andcentering slits b for receiving the ends of the usual adjusting screws(Z of the instrument, whereby the latter is leveled in usual manner.Instead of locating said centering slits b, as shown, they may be placedcentrally in the top surface a of the trivet, as shown at (4", Figs. 2and 3, when the trivet is used with instruments which do not require theshifting adjustment for which the shifting ring Z) is provided, the ideabeing simply to provide a centering means or positioning slit which willmaintain the lower ends of the adjusting screws in unalterable relativeposition.

In both embodiments of my invention, the plane top surface which extendslaterally integrally from the hub, supports the ad justing screws of theinstrument head, said screws being supported thereby in direct contactwith the slits a when no shifting movement is required, and said screwsbeing supported thereby for free shifting movement by being mounted indirect con tact with the slits b of the interposed shifting ring whenshifting is required.

In use the instrument head is removed from its regular tripod and isplaced on top of the trivet, its adjusting screws being centered eitherin the slits b or a (the former being required for a transit, forexample, and the latter for a leveling instrument). Thereupon the stem 0is rotated by its end a into threaded engagement with the part (Z of theinstrument-head and is then clamped to the trivet by rotating the starnut If the instrument is a transit or the like, the cap-like nut b isfirst loosened, before attempting the above centering operation therebypermitting the entire instrument to be shifted with the supporting ring71 in any direction, and when it is finally brought into absolutelycorrect position, it is secured and clamped in the manner above setforth.

My invention enables the surveying instrument to be placed solidly onthe ground or timber low down so as to occupy very little space and yetthe trivet base is broad, extending laterally beyond the instrumentheadsupports or adjusting screws 4, so as to provide against accidentaltipping, and the construction is such that the trivet is not only broadbut heavy and stable, while yet permitting all the adjustments andprecision of position which have heretofore been secured in the ordinarytripod construction as used on the surface where the operator has beenable to stand upright and manipulate his instrument with freedom ofmovement and position. My object is to obtain the same results in thecramped, limited space of a low stoping or drift, or the like, in minework.

I do not intend to limit myself to all the details of constructionherein set forth, as

my invention is capable of many other embodiments within the spirit andscope of the following claims.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is:

1. A trivet for surveying instruments, having a central hub providedwith an opening extending through from top to bottom,

and adjustable means extending vertically through said hub for retainingthe instrument-head, said trivet having plane top surface extendinglaterally integrally from said hub for supporting the adjusting screwsof the instrument-head, and short, rigid and branching legs beneath saidtop surface and immovable with relation thereto.

2. A trivet for surveying instruments, comprising a. heavy central hubhaving a plurality of integral legs extending radially and all lying inapproximately a horizontal plane, said legs and hub being thick andheavy for giving stability of position to the instrument and havingtheir top surfaces flat, horizontal all in one plane and adapted topermit sliding movement in all directions of a superposed flat part, tosustain the adjusting screws of the instrument, and provided with acenter vertically open from top to bottom and means cooperating withsaid center for retaining the instrument-head rigidly thereon.

A trivet for surveying instruments, having central means for retainingthe instrument-head, a plane top surface extending laterallyco-exteusively of the entire top of the trivet for supporting theadjusting screws of the instrument-head, radial centering grooves formedin said plane top surface for said adjusting screws, and short, rigidand branching legs beneath said top surface.

l. A trivet for surveying instruments, comprising a rigid, low supporthaving branching legs, a central retaining device for clamping theinstrument-head fast against lateral movement, and means for shiftingthe instrument laterally of said legs without moving with it saidcentral retaining device.

5. A trivet for surveying instruments, comprising a rigid, low supporthaving branching legs, a central clamp for clamping the instrument-headfast against lateral movement, and shifting means for said 1nstrumenthead provided with means for receiving in unvarying position theadjusting screws of the instrument-head, said shifting means beingcapable of shifting the instrument and said adjusting screws laterallyof said legs in all directions without shifting said central clamp.

6. A trivet for surveying instruments, comprising a rigid, low support,having a heavy central hub containing a central vertical cup-shapedcavity with a narrow inwardly extending flange at its under side and athreaded annulus at its upper side, branching legs extending laterallyfrom said hub and terminating in short pointed feet.

7. A trivet for surveying instruments, comprising a rigid, low support,having a heavy central hub containing a central vertical eupshapedcavity, laterally branching legs extending from said hub, said trivethaving a plane top surface extending laterally from said hub to receivethe superposed parts of the surveying instrument and permit the lat terto be shifted freely thereon in all directions. said legs having theirlower and upper sides extending respectively from the bottom portion ofsaid hub and the outer portion of the plane top of the trivet and henceconverging toward the outer ends of the legs.

8. A trivet for surveyinginstruments, comprising a rigid, low support,having a heavy central hub containing a central vertical eupshapedcavity, laterally branching legs extending from said hub, said trivethaving a plane top surface extending laterally from said hub to receivethe superposed parts of the surveying instrument and permit the latterto be shifted freely thereon in all directions, said legs having theirlower and up per sides extending respectively from the bottom portion ofsaid hub and the outer portion of the.plane top of the trivet and thenceconverging toward the outer ends of the legs, said terminating inlntegral dependlng stub-like pointed feet.

9. A trivet for surveying instruments, com

prising a rigid, low support, having a heavy central hub containing acentral vertical cupshaped cavity, laterally branching legs extendingfrom said hub, said trivet having a plane top surface extendinglaterally from said hub to receive the superposed parts of the surveyinginstrument and permit the latter to be shifted freely thereon in alldirec tions, said legs having their lower and upper sides extendingrespectively from the bottom portion of said hub and the outer portionof the plane top of the trivet and thence converging toward the outerends of the legs, each leg also having its opposite upright sidesconverging toward its top and diverging from the outer end of the legalong its bottom portion to the hub, whereby the leg is broader at itsbottom side than in its upper portion and is \vide' and heavier at thehub than at its outer end.

' In testimony whereof. l have signed my name to this specification, inthe presence of two subscribing witnesses.

Cl-llll i T [AN ll. l3 EliGEl-t. \Vitnesses GEO. H. lvlaxwnim, ,M. A.Jones.

